Monitoring turbidity in San Francisco Estuary and Sacramento-San Joaquin Delta using satellite remote sensing

Abstract:

This study utilizes satellite data to investigate water quality conditions in the San Francisco Estuary and its upstream delta, the Sacramento-San Joaquin River Delta. To do this, this study derives turbidity from the European Space Agency satellite Sentinel-2 acquired from September 2015 to June 2019 and conducts a rigorous validation with in situmeasurements of turbidity from optical sensors at continuous monitoring stations. This validation includes 965 matchup comparisons between satellite and in situ sensor data across 22 stations, yielding R2=0.63 and 0.75 for NTU and FNU stations, respectively. This study then uses remote sensing-derived turbidity to evaluate patterns in turbidity during the Suisun Marsh Salinity Control Gates Action (“Gates action”), a pilot study designed to increase habitat access and quality for the endangered Delta Smelt. The basic strategy was to direct more freshwater into Suisun Marsh, creating more low salinity habitat that would then have higher (and more suitable) turbidity than upstream river channels. For all seven acquisitions considered from June 29 to September 27, 2018, 2018, turbidity conditions in Bays and Sloughs sub-regions were consistently higher (and more suitable) (26-47 FNU) than what was observed in upstream River region (13-25 FNU). This overall pattern was observed when comparing images acquired during similar tidal stages and heights.